1. Field of the Invention
The present invention relates to a support platform of a non-contact transfer apparatus, and more particularly, to a support platform that can transfer objects under a non-contact state.
2. Discussion of the Related Art
Generally, in order to manufacture a semiconductor integrated circuit or a display panel, an object (for example, a substrate) undergoes a plurality of processes. In order to transfer the object from one process to another process, a transfer apparatus is used. A transfer apparatus that can efficiently transfer the object has been studied.
The transfer apparatuses are classified into contact transfer apparatuses that can transfer the object in a state where the object directly contacts a support platform and non-contact transfer apparatuses that can transfer the object in a state where the object is lifted by air pressure. In the case of the contact transfer apparatus, since the object is transferred in a state where it contacts the support platform, the object may be scratched due to friction between the object and the support platform or broken because of contact with the support platform. In the case of the non-contact transfer apparatus, since the object is transferred without contacting the support platform, the damage of the object may be minimized or be prevented and pollution to the object by foreign objects can be lowered. Furthermore, there is no electrostatic problem caused by the contact between the object and the support platform. Because of these apparent benefits, the non-contact transfer apparatus has been more actively studied.
FIG. 1 shows a support platform of a non-contact transfer apparatus according to the related art of the present invention.
In FIG. 1, a prior art support platform 100 of a non-contact transfer apparatus includes a plurality of unit cells each having a chess-table format. The unit cells are provided with a plurality of air intake hole portions 101 and a plurality of air exhaust holes 102. Air is sprayed toward an object 106 through the air intake hole portions 101 and is then exhausted to an external side through the air exhaust holes 102. In this case, intervals between the air intake hole portions 101 are identical to each other. Likewise, intervals between the air exhaust hole 102 are identical to each other. The air intake and exhaust holes 101 and 102 are identical in diameter to each other. Also, pitches between the air intake hole portions 101 and the air exhaust holes 102 are identical to each other.
When the object 106 that may have a size equal to, greater, or less than that of an active surface 107 of the platform 100 is arranged close to and parallel the active surface 107, an air cushion 104 is formed between a bottom surface of the object 106 and the active surface 107. The air cushion 104 provides an intensity of the pressure for uniformly lifting the object 106. The intensity of the pressure depends on an amount of air introduced through the air intake hole portions 101 and an amount of air exhausted through the air exhaust holes 102.
The object 106 may be transferred in the arrow direction in FIG. 1. The air intake hole portions 101 are connected to a pressure storing unit 108 connected to an air pump 109. Therefore, the air sucked by the air pump 109 is stored in the pressure storing unit 108 and is then sprayed through the air intake hole portions 101. The sprayed air forms the air cushion 104 to transfer the object in a state where the object 106 is lifted from the active surface 107 of the platform 100 by a predetermined interval.
In the non-contact transfer apparatus of the related art, because each air intake hole 101 through which the air is introduced has a predetermined diameter, a large amount of air is consumed to form the air cushion 104 on the active surface 107, thereby increasing the process costs.
In addition, since not only the pitches between the holes 101 and 102 but also the diameters of the holes 101 and 102 are identical to each other, as shown in FIG. 2, the pressure at the central portion of the support platform is greater than that at the peripheral portion of the support platform. That is, the pressure distribution is not uniform throughout the active surface of the support platform. Therefore, the object lifted from the platform may jolt or collide with a peripheral object. The jolting or colliding causes damage to the object. Therefore, there is a need to uniformly form air pressure through the active surface of the platform.